BC or Before Christ refers to the number of years before Christ was born. AD or Anno Domini refers to the period after Christ was born. CE means common (or current) era”, while BCE means ”before the common (or current) era”.

The short answer is that BC and BCE both refer to years before the birth of Jesus Christ, and AD and CE both refer to years after the birth of Jesus Christ. BC and AD reference Christ’s birth directly, while BCE and CE are more secular ways to tell time.

The abbreviation BC stands for “before Christ,” while AD stands for annō Dominī, which translates to “in the year of the lord.” The lord that’s being referenced, as BC hints at, is Jesus Christ. The alternative to using BC and AD would be to use BCE, which means “before Common Era,” and CE, which means “Common Era.”

The two systems —BC and AD, and BCE and CE— are numerically equivalent and indicate exactly the same dates. The BCE/CE notation system is simply the religiously neutral alternative to BC/AD. In scholarly literature, BCE and CE are now often preferred.